Solid axle wheel support and sealed bearing construction

ABSTRACT

Bearing assembly for a wheel primarily for use in casters produced under high production conditions. The bearing is characterized by the provision of a solid shaft with staked ends in association with a resilient seal all arranged for producing a bearing capable of inexpensive manufacture under high production conditions, but also a bearing having close tolerances and thereby capable of long and accurate operation.

FIELD OF THE INVENTION

The invention relates to bearing assemblies primarily for caster wheelsproduced under high production conditions such as the wheels used forshopping carts, small trucks and similar type devices.

BACKGROUND OF THE INVENTION

Although a variety of ball bearings and ball bearing assemblies havebeen devised in the past for meeting limitless situations where frictionmust be minimized, a constant effort is being made to improve theeffectiveness of such bearing assemblies while simultaneously loweringtheir cost. This is of particular importance where the bearings aremanufactured in large quantities for a variety of purposes, such as incaster wheels, conveyor wheels, small truck wheels and in wheels forother vehicles or generally similar nature. Where the production of suchbearing assemblies is on the order of several hundred or more per hour,it is apparent that even a small reduction in the unit cost of a bearingassembly will result in greater savings, both to the manufacturer of thebearing assemblies and to the users thereof. On the other hand, in viewof the critical part played by such bearing assemblies in practicallyall of their usual locations of use, it is equally apparent that suchcost reductions, if any, must be made without sacrificing quality.

Bearings and the wheels associated therewith of this general nature havelong been known and many such bearings of the type shown and describedin U.S. Pat. No. 3,807,817, assigned to the same assignee as the presentapplication, have long been known. However, in a continuing effort toimprove the quality of the product while at the same time reducing itscost, a great deal of effort has been made to detect points in theprevious devices at which such improvements and/or cost reductions canbe made. Thus, in such wheels and their bearing assemblies as shown insaid patent, as well as in other generally similar patents such U.S.Pat. Nos. 3,881,789 and 1,674,087, there are shown axles for the supportof the bearings which in turn support the wheels, which axles are hollowand held in place by a fastener, such as a pin or bolt, passedtherethrough. This is effective in operation but it involves the step ofboring the hole for such fastener and the further step of inserting suchfastener therein, all of which steps involve expense. Furher, in theassembly of U.S. Pat. No. 3,807,817, reliance is placed for sealing ofthe bearing on relatively small bearing seals associated therewith whichare separate items involving expense in both the provision thereof andin the assembly thereof and at the same time are relatively small anddepend upon their own resiliency for holding themselves in position. Itis accordingly desirable to eliminate these seals entirely and thuseliminate the above-mentioned expense resultant therefrom and at thesame time to provide for a more efficient and effective dust seal toprotect the bearing balls and races.

Accordingly, the objects of the invention include:

1. To provide a bearing and wheel construction adaptable for use underhigh production conditions which will produce a very inexpensive wheeland yet one which will be solid, firm and capable of long and accurateoperation.

2. To provide a bearing and wheel construction, as aforesaid, which willeliminate some of the manufacturing steps now required in certainpresent constructions of this type but will do so without sacrifice inquality of the resultant product.

3. To provide a bearing and wheel construction, as aforesaid, whereinthe separate sealing means now required can be eliminated withoutsacrifice in the quality of the resultant product.

4. To provide a bearing and wheel construction, as aforesaid, which willhave other advantages and economies recognized by persons skilled in theart but which will at the same time provide a bearing capable ofwithstanding substantial abuse and requiring only minimal maintenance,such as is recognized as required for a variety of commercialapplications, such as use in shopping carts.

Other purposes and advantages of the invention will be apparent topersons acquainted with apparatus of this general type upon reading thefollowing specifications and inspection of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an elevational view of a wheel, here a caster wheel, embodyingthe invention; and

FIG. 2 is a fragmentary sectional view taken on the line II--II of FIG.1.

SUMMARY OF THE INVENTION

Briefly, the invention contemplates the provision of a wheel having acentral opening therethrough with a sleeve received into said openingand the outer races of a pair of bearing assemblies positioned atopposite ends of said sleeve. A central solid shaft is coaxial andinternal of said sleeve and carries adjacent its ends the inner races ofsaid bearing assemblies. Appropriate bearing elements are positionedbetween the races. The respective ends of said sleeve extend axiallybeyond the bearing assemblies and are each engaged by an end plate, saidend plate being preferably of somewhat resilient material and seated onsaid shaft. The ends of said shaft are then staked against a suitablefork by which said wheel is supported and the fork structure is causedto bear against said end plates for holding same snugly and in dustsealing relationship with the axial ends of said sleeve.

DETAILED DESCRIPTION

FIG. 1 illustrates a swivel caster 10 which includes an invertedU-shaped frame 11 having a pair of parallel legs 12 and 13 straddlingthe wheel 14. Said wheel also includes a bearing assembly 17 mounted inthe central opening 16 of the wheel. An axle 20 extends through thebearing assembly 17 and through a pair of axially aligned openings 18and 19 in the legs 12 and 13 respectively. The bearing assembly 17includes a generally tubular thermoplastic bearing sleeve 21 which ismounted within the opening 16. The opposite axial ends of plastic sleeve21 respectively have radially extending flanges 22 and 23 which extendbeyond the correspondingly adjacent surfaces of the wheel 14 ashereinafter further described in more detail.

The wheel 14 comprises an annular portion 24 of any desired shape whichis fixed in any convenient manner to the sleeve 21, here by athermoplastic locking ring 26 which is molded into place between theannular portion 24 and the bearing sleeve 21. This structure isdescribed in detail in my copending application Ser. No. 723,927, filedSept. 16, 1976.

The bearing sleeve 21 is provided with outer races 27 and 28 which maybe, as in this instance, respectively provided with antifriction raceliners 31 and 32.

The axle 20 is solid and is provided with shoulders 33 and 34 for thelocating of the legs 12 and 13. The axle 20 has an initial shape at itsends 36 and 37, as indicated by the broken lines in FIG. 2, whichproject through the openings 18 and 19 and are then each upset againstthe legs 12 and 13 for holding same snugly against the shoulders 33 and34. The axle is thus fixed firmly in place, held rigidly to said legsand assists in holding said legs rigidly with respect to each other.

Said axle has further shoulders 38 and 39 which locate a pair of endcaps 41 and 42 further discussed hereinafter and said axle also hasflanges 43 and 44 which define inner bearing races 46 and 47. Said innerbearing races may, as here, be provided with antifriction liners 48 and49. A series of balls of which two are shown at 51 and 52 occupy in aconventional manner the space between the bearing races or, in thisinstance, the spaces between respectively facing surfaces of the raceliners.

Turning now again to the end caps 41 and 42, it will be seen that theyare identical but are assembled facing oppositely from each other so asin FIG. 2 to appear as mirror images of each other. Turning first to theend cap 41, same is provided at its radially inner edge with a footportion having a radial section 56 and an axial section 57. When ininstalled position, said radial section 56 bears snugly against and isaxially limited by the shoulder 38 while the axial section 57 bearssnugly against and is supported by the peripheral surface of said axle20 which is adjacent to said shoulder 38. The end cap then extendsradially outwardly and axially away from the center of the bearingassembly to a central portion 58 which bears against the inner surfaceof the leg 12. Said central portion 58 has an annular seal 59 extendingaxially centrally of the bearing assembly sufficiently to be in contactwith the outwardly facing end of the flange 22. The parts are soproportioned that when the end 36 of the axle is upset as shown in solidlines in FIG. 2, the leg 12 will not only be urged snugly against theshoulder 33 but will also be urged snugly against the central section 58of the end cap 41 and the annular flange 59 urged snugly against the endflange 22 of the sleeve 21. Likewise such urging of the central section58 also urges the radial portion 56 of said end cap snugly against theshoulder 38 of the axle. Said end cap may if desired be provided with aninwardly extending portion 61 partly for the sake of appearance andpartly for the further protection of the seal area formed by the flange59 and end 22.

Thus, the end cap, or dust cap, 41 also constitutes the seal for thebearing and same is held snugly in sealing position by the singleupsetting step by which the end 36 of the axle is upset for holding theleg 12 solidly in position.

The leftward end of the apparatus including the dust cap 42, the flange23 and end 37 of the axle are all as seen in FIG. 2 mirror images of theparts above described in connection with the rightward (as seen in FIG.2) portions of the described device and it will be evident uponinspection of the drawing in the light of the description already givenfor the rightward side of the device and hence no further descriptionneeds to be given with respect thereto.

ASSEMBLY

The assembly has been somewhat indicated above but will be reviewed toinsure a complete understanding of the invention.

With the liners 48 and 49 positioned in any conventional manner (as bybeing split or by being sufficiently resilient to go over the adjacentflanges 43 and 44 or installed in accordance with the teaching in myU.S. Pat. No. 3,807,817), the balls are inserted in any conventionalmanner and the sleeve 21 and associated liners are assembled therewithin any conventional manner. The bearing assembly and axle thus assembledare now held in appropriate position with respect to the wheel annulus24 and a locking strip 26 molded in place for locking the bearingassembly rigidly into position within the wheel annulus 24 as taught inmy aforesaid application Ser. No. 723,927, filed Sept. 16, 1976. The endcaps 41 and 42 are placed in position against the shoulders 38 and 39,the legs 12 and 13 snapped into place over the axle ends 36 and 37 andthe axle ends then upset tightly against the legs 12 and 13 as shown.

This results in an extremely simple but strong structure, insures arigid holding of the axle with respect to the legs 12 and 13 as well asa rigid holding of the legs with respect to each other. It furtherinsures a firm sealing of the end caps against the central sleeve 21 foreffecting a sealing of the bearing zone and thereby eliminates theseparate bearing seals which have been conventionally used in priorknown devices.

Although a particular preferred embodiment of the invention has beendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of the disclosed apparatus, includingthe rearrangement of parts lie within the scope of the presentinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A wheel construction fora tire having a central coaxial opening therethrough, comprising:acylindrical sleeve fixedly disposed in said central opening in saidtire, said sleeve having a portion of reduced inside diameter spacedfrom both axial ends thereof; a pair of outer bearing races snuglydisposed within said sleeve against the opposite axial ends of saidportion of reduced diameter; a solid cylindrical axle having spacedportions of reduced diameter defining spaced shoulders near the oppositeends thereof, said axle being disposed coaxially within and spaced fromsaid reduced portion of said sleeve and extending axially beyond bothends thereof; a pair of inner bearing races encircling said axle andradially aligned with said outer bearing races and antifriction meanspositioned between respective pairs of said bearing races; a pair ofaxially spaced first upset portions on said axle located between saidshoulders and pair of inner bearing races to fixedly hold said innerbearing races to said axle, said first upset portion defining a sealshoulder between said inner bearing races at one end of said axle andthe respectively adjacent shoulder and including a generally circularand resiliently flexible end cap encircling said axle and bearingagainst said seal shoulder; frame legs encircling said axial extensionsof said axle and bearing snugly against said shoulders and a secondupset portion at the end of each axial extension bearing against the legadjacent thereto and holding same firmly against the respectivelyadjacent shoulder, said end cap having a portion thereof extendingaxially outwardly from said shoulder to bear against the inner face ofthe axially adjacent frame leg and said end cap further having anannular seal ring on the inner surface thereof bearing against theadjacent end of said cylindrical sleeve, the parts being so proportionedthat when said frame leg is in position against said shoulder, the endcap is urged snugly against the seal shoulder and the annular seal ringthereof urged against the adjacent end of said cylindrical sleeve;whereby said inner bearing races are locked permanently to said axle andsaid frame legs are locked permanently and firmly with respect to saidaxle and through said axle held rigidly with respect to each other allby the material of said solid axle.
 2. The wheel construction accordingto claim 1, wherein said cylindrical sleeve has an axial extensionthereon extending axially beyond the bearing race associated with saidsleeve for engagement with said annular seal ring.
 3. The wheelconstruction according to claim 2, wherein said end cap is of resilientmaterial for absorbing variations in tolerance and maintaining a snugsealing relationship against and with respect to said axle and saidaxial extension on said cylindrical sleeve.
 4. A wheel construction fora tire having a central coaxial opening therethrough, comprising:acylindrical sleeve fixedly disposed in said central opening in saidtire, said sleeve having a portion of reduced inside diameter spacedfrom both axial ends thereof; a pair of outer bearing race means locatedat the opposite axial ends of said portion of reduced diameter; a solidcylindrical axle having spaced portions of reduced diameter definingspaced shoulders near the opposite ends thereof, said axle beingdisposed coaxially within and spaced from said reduced portion of saidsleeve and extending axially beyond both ends thereof; a pair of innerbearing race means on said axle and radially aligned with said outerbearing race means and antifriction means positioned between respectivepairs of said bearing race means; frame legs encircling said axialextensions of said axle and bearing snugly against said shoulders andmeans at the end of each axial extension bearing against the legadjacent thereto and holding same firmly against the respectivelyadjacent shoulder; a seal shoulder on said axle between said innerbearing race means at one end of said axle and the respective adjacentshoulder; a generally circular end cap made of a compressiblethermoplastic material encircling said axle and bearing against saidseal shoulder, said end cap having a portion thereof extending axiallyoutwardly from said shoulder to bear against the inner face of theaxially adjacent frame leg and said end cap further having an annularseal ring on the inner surface thereof bearing against the adjacent endof said cylindrical sleeve, the parts being so proportioned that whensaid frame leg is in position against said shoulder, the end cap isurged snugly against the seal shoulder and the annular seal ring thereofurged against the adjacent end of said cylindrical sleeve; whereby saidframe legs are held firmly with respect to said axle and through saidaxle held rigidly with respect to each other and said annular seal ringof said compressible end cap is compressed between said frame legs andsaid cylindrical sleeve for sealing said bearing means from dust. .Iadd.5. A wheel construction for a tire having a central coaxial openingtherethrough, comprising:a cylindrical sleeve (21) fixedly disposed insaid central opening in said tire, said sleeve having a portion ofreduced inside diameter spaced from both axial ends thereof and acylindrical extension defining a first annular seal surface (52,53)integrally provided at opposite axial ends thereof; a pair of outerbearing race means (38,39) located at the opposite axial ends of saidportion of reduced diameter; a cylindrical axle (20) disposed coaxiallywithin and spaced from said reduced portion of said sleeve; a pair ofinner bearing race means (41,42) on said axle and radially aligned withsaid outer bearing race means and anti-friction means (43) positionedbetween respective pairs of said bearing race means; frame legs (12,13)and securement means (56,57,58) for effecting an operative connection ofsaid frame legs to said axle; a seal shoulder (A) on said axle spacedaxially inwardly along said axle from both of the ends thereof; agenerally circular end cap (48,49) made of a compressible thermoplasticmaterial encircling said axle and having integral seal means (50,51)bearing against said seal shoulder, said end cap having an axial section(B) thereof extending axially from said seal means to bear against theinner face of the axially adjacent frame leg and said end cap furtherhaving an integral second annular seal surface (C) thereon spacedradially outwardly from said axial section bearing against said firstannular seal surface (52,53), the parts being so proportioned that whensaid frame legs are in position adjacent the ends of said axle, saidseal means (50,51) on said end cap is urged snugly against said sealshoulder (A) and said first (52,53) and second (C) annular seal surfacesurged into engagement with each other; whereby said frame legs are heldfirmly with respect to said axle and through said axle and saidsecurement means held rigidly with respect to each other and said secondannular seal surface of said compressible end cap is urged intoengagement with said first annular seal surface on said cylindricalsleeve for sealing said bearing means from dust. .Iaddend.